Increased plasma conc w/ azole antifungals, macrolides, amiodarone HCl, grapefruit juice. Increased blood conc of TCAs, butyrophenone, antipsychotics, flecainide, vinblastine. Decreased serum Ca level w/ calcitonin, bisphosphonate bone absorption suppressors, corticosteroids. Affected plasma conc w/ digitoxin, diazepam.